Is this a serviceable part or do I need to buy a new housing? Bike has 2100 miles ( 07 ), bought as a left over this may . I rarely use the rear , except for pulling a u turn or stop and go , WTF

Is the leak at the hose going to the rear brake or actually on the inlet of the master cylinder?
If it is on the inlet (the plastic elbow thingy) push it back in properly, it is only held in by an O-ring I believe, and strain from the rubber hose makes it pop out.
You might have to bleed it after fixing it.
However I'm not sure that's where the leak is from, could be the hose or a split at the bottom of the reservoir.

EDIT: it could also leak from the switch and pushes the oil out via the electrical wires and rubber cap.

I take it you are in the USA? If so, take it to your dealer because its still under warranty.